Modern electronic devices, and particularly integrated circuits, are at risk of damage due to electrostatic discharge (ESD) events. During an ESD event, a voltage (or current) can be provided to one or more terminals of the electronic device that causes the voltage between those terminals to exceed the maximum designed voltage of the electronic device. Such an event can impair subsequent operation of the electronic device. For example, a voltage at a terminal of the electronic device during an ESD event can exceed a breakdown voltage of one or more components of the electronic device, and thereby potentially damage those components. Accordingly, electronic devices often include an ESD protection device that provides protection from excessive voltages during ESD events.
To avoid interfering with normal operation of the electronic device being protected, the ESD protection device typically is designed to turn on and to conduct current when an applied voltage exceeds an operating voltage of the electronic device but before the applied voltage exceeds the breakdown voltage of the electronic device. In practice, there often is a difference between a transient triggering voltage and a steady state (or direct current) voltage that can be maintained by the ESD protection device. This voltage difference can make it difficult for the ESD protection device to fit within the design window defined by the respective operating and breakdown voltages of the electronic device to be protected (or alternatively, constrains the circuit designer to operating and breakdown voltages that accommodate the difference in the triggering voltage and the steady state voltage of the ESD protection device). In addition, ESD protection devices often exhibit a significant voltage overshoot during rapid voltage transients. This voltage overshoot can cause the voltage experienced by the electronic device being protected to exceed the breakdown voltage thereof. Furthermore, when multiple ESD protection devices are used to provide higher levels of ESD voltage protection, the voltage overshoot is multiplied, which further constrains circuit designers or increases a potential for damage to the electronic device being protected.